The susceptibility towards proteolysis of intermediates during the renaturation of yeast phosphoglycerate mutase.

The renaturation of the tetrameric enzyme phosphoglycerate mutase from baker's yeast after denaturation in guanidinium chloride was studied. Three proteinases (trypsin, chymotrypsin and thermolysin) cause extensive loss of activity of samples taken during the early stages of refolding. As judged by SDS/polyacrylamide-gel electrophoresis, the proteinases cause substantial degradation of the polypeptide chain with no evidence for large quantities of fragments of Mr greater than 6500. These data suggest that the early intermediates in the refolding, especially the folded monomer, possess a number of sites that are susceptible to proteolysis.